Alien Moths Are Coming for Your Nuts

Invasive species threaten wood and nuts all around the globe. Here in the U.S., you can Kiss Your Ash Goodbye thanks to the Emerald Ash Borer, and the Asian Longhorned Beetle likes to munch on a variety of hardwoods. In the UK, it’s an invasive moth species that’s making chestnuts shrivel up.

In just-published research, scientists used observations by the general public to map the spread of that invasive moth, and also test hypotheses about how native species respond:

The Horse-Chestnut Leaf-Miner moth was first observed in 2002 at Wimbledon, and is thought to have hitch-hiked on luggage or plant material brought in by a traveler. The moth attacking UK’s conkers is quite tiny — less than 5mm long. Its caterpillars tunnel between cell layers of leaves, causing unsightly discoloration. Infested horse chestnut leaves turn brown and wither up, occasionally falling off.

Moth Invasion! Model of the spread of the Horse Chestnut Moth from its 2002 introduction at Wimbledon.

The UK researchers tested two hypotheses: First, they wondered if there would be more leaf damage observed the longer the moth had been present in an area. They also wondered how many generations a year the moth had, and how fast the moth was spreading.

For their second hypothesis they wanted to know how often the moths were parasitized. In theory, the longer the introduced moths had been present, the more likely it was that local predators and parasites might begin to attack them. But trying to track a tiny insect over an entire island is a big job for two scientists. And that’s when they brought their science to the people.

Not only did the researchers get enough data to test their population spread models (it looks like the moth has 2 generations a year, not three), they now have an existing web and phone app infrastructure that will let them conduct further studies.

If you have a smartphone and an interest in nature, please do participate in a citizen science project! There are many great bird and insect programs out there. In a time of shrinking budgets for both households and science, this is free fun that can also contribute important information.